This Shared Instrumentation grant application is for the purchase of a new flow cytometer/cell sorter to serve the Flow Cytometry Core Facility at The Cornell University Medical College. The Core facility is part of the NIH-funded Cornell Multipurpose Arthritis and Musculoskeletal Diseases Center and is staffed by a full-time flow cytometer technician. Decreased reliability and technical limitations of our current instrument, markedly increased needs of our current users and recruitment of new NIH-supported faculty with essential flow cytometry and cell sorting needs make acquisition of a new instrument a critical priority for our user's group which consists of 18 NIH-funded investigators, supported by 20 individual ROl-type grants and 5 PO1/P6O-type grants, and 3 promising young investigators, each with federal support currently pending.